ORA-24777: use of non-migratable database link not allowed Cause: The transaction, which needs to be migratable between sessions, tried to access a remote database from a non-multi threaded server process. Action: Perform the work in the local database or open a connection to the remote database from the client. If multi threaded server option is installed, connect to the Oracle instance through the dispatcher.

ORA-24778: cannot open connectionsCause: The migratable transaction tried to access a remote database when the session itself had opened connections to remote database(s). Action: Close the connection(s) in the session and then try to access the remote database from the migratable transaction. If the error still occurs, contact Oracle customer support.